AIR CONDITIONING SYSTEM, Diagnostic DTC:B1423/23

DTC Code DTC Name
B1423/23 Pressure Sensor Circuit

DESCRIPTION

This DTC is stored if refrigerant pressure on the high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more). The air conditioner pressure sensor, which is installed on the high pressure side pipe to detect refrigerant pressure, sends a refrigerant pressure signal to the air conditioning amplifier assembly. The air conditioning amplifier assembly converts this signal to a pressure value according to the sensor characteristics and uses it to control the compressor.

DTC No. Detection Item DTC Detection Condition Trouble Area Memory
B1423/23 Pressure Sensor Circuit
  • Open or short in air conditioner pressure sensor circuit

  • Refrigerant pressure on high pressure side is extremely low (176 kPa (1.8 kgf/cm2, 26 psi) or less) or extremely high (3025 kPa (30.8 kgf/cm2, 439 psi) or more)


  • Air conditioner pressure sensor

  • Harness or connector between air conditioner pressure sensor and air conditioning amplifier assembly

  • Air conditioning amplifier assembly

  • Cooler expansion valve (blocked, stuck)

  • Cooler condenser assembly (blocked, deterioration of cooling capacity due to dirt)

  • Cooler dryer (moisture in the refrigerant cycle cannot be absorbed)

  • Cooling fan system (cooler condenser assembly cannot be cooled down)

  • Air conditioning system (leaks, blocked)

-

WIRING DIAGRAM

B003YQWE36
*a Air Conditioner Pressure Sensor
*b Air Conditioning Amplifier Assembly

CAUTION / NOTICE / HINT

Tech Tips

If DTC B1423/23 and B14B8 are output at the same time, troubleshoot for DTC B1423/23 first.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (POWER SOURCE CIRCUIT)


    1. Disconnect the B5 air conditioner pressure sensor connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      B5-3 (+) - Body ground Power switch on (IG) 4.75 to 5.25 V
      Result
      Proceed to
      OK
      NG

    NG
    OK
  2. CHECK HARNESS AND CONNECTOR (GROUND CIRCUIT)


    1. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      B5-1 (-) - Body ground Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    NG
    OK
  3. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Reconnect the B5 air conditioner pressure sensor connector.

    2. Remove the air conditioning amplifier assembly with the connectors still connected.

    3. B003XPUC11
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K11-9 (PRE) - Body ground

      Power switch on (IG)

      (A/C switch: Off)

      0.74 to 4.71 V

      Tech Tips

      If the measured voltage is not within the normal range, there may be a malfunction in the air conditioning amplifier assembly, air conditioner pressure sensor, or wire harness. It is also possible that the amount of refrigerant may not be appropriate.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  4. INSPECT AIR CONDITIONER PRESSURE SENSOR (SENSOR SIGNAL CIRCUIT)


    1. Measure the voltage when the following conditions are met.

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)

      Note


      • If refrigerant pressure on the high pressure side becomes extremely high during the inspection (if the voltage exceeds 4.71 V), the fail-safe function stops compressor operation. Therefore, measure the voltage before the fail-safe operation.

      • It is necessary to measure the voltage for a certain amount of time (approximately 10 minutes) because the malfunction may recur after a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the thermistor assembly and the No. 1 cooler thermistor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.


      1. B003XPUC11
        *a

        Component with harness connected

        (Air Conditioning Amplifier Assembly)

        Measure the voltage according to the value(s) in the table below.

        Standard Voltage
        Tester Connection Condition Specified Condition
        K11-9 (PRE) - Body ground

        Power switch on (IG)

        (A/C switch: On)

        0.74 to 4.71 V
      Result
      Result Proceed to
      OK (When troubleshooting according to DTC) A
      OK (When troubleshooting according to Problem Symptoms Table) B
      NG C

    A
    B
    C
  5. INSPECT COOLING FAN SYSTEM


    1. Check if the cooling fan operates normally.

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  6. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      Click here

      Tech Tips

      If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

      Result
      Proceed to
      NEXT

    NEXT
  7. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the thermistor assembly and the No. 1 cooler thermistor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC. If the DTC is not output after this work, it indicates that the cooler dryer in the cooler condenser assembly is not able to absorb moisture in the refrigerant cycle. It is necessary to replace the cooler dryer in order to complete the repair.

      Result
      Result Proceed to
      DTC B1423/23 is output A
      DTC B1423/23 is not output B

    B
    A
  8. REPLACE COOLER EXPANSION VALVE


    1. Replace the cooler expansion valve with a new one.

      Click here

      Tech Tips

      Replace the cooler expansion valve with a new one because the cooler expansion valve is either stuck or clogged.

      Result
      Proceed to
      NEXT

    NEXT
  9. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      Click here

      Tech Tips

      If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

      Result
      Proceed to
      NEXT

    NEXT
  10. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips


      • When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the thermistor assembly and the No. 1 cooler thermistor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      • If refrigerant pressure is not normal after replacing the cooler expansion valve with a new or known good one, the cooler condenser assembly or pipes may be clogged due to dirt, dust or other foreign matter. In this case, clean or replace the cooler condenser assembly or pipes.

      Result
      Result Proceed to
      DTC B1423/23 is not output A
      DTC B1423/23 is output B

    A
    B
  11. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR)


    1. Disconnect the B5 air conditioner pressure sensor connector.

    2. Disconnect the K11 air conditioning amplifier assembly connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      B5-2 (PR) - K11-9 (PRE) Always Below 1 Ω
      K11-9 (PRE) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    OK
  12. INSPECT FOR AIR CONDITIONING SYSTEM LEAK


    1. Install a manifold gauge set.

    2. Recover the refrigerant from the air conditioning system using a refrigerant recovery unit.

    3. Evacuate the air conditioning system and check that vacuum can be maintained.

      OK
      Vacuum can be maintained in the air conditioning system.

      Tech Tips

      If vacuum cannot be maintained in the air conditioning system, refrigerant may be leaking from it. In this case, it is necessary to repair or replace the leaking part of the air conditioning system.

      Result
      Proceed to
      OK
      NG

    NG
    OK
  13. CHARGE SYSTEM WITH REFRIGERANT


    1. Use a refrigerant recovery unit to recover refrigerant.

    2. Evacuate the air conditioning system.

    3. Add an appropriate amount of refrigerant.

      Click here

      Tech Tips

      If refrigerant is added and the system has not been properly evacuated (insufficient vacuum time), moisture in the air remaining in the system will freeze in the cooler expansion valve, blocking the flow on the high pressure side. Therefore, in order to confirm the problem, recover the refrigerant and properly evacuate the system. Add an appropriate amount of refrigerant, and check for the DTC.

      Result
      Proceed to
      NEXT

    NEXT
  14. RECHECK FOR DTC


    1. Recheck for the DTC when the following conditions are met.

      Item Condition
      Vehicle doors Fully open
      Temperature setting MAX COLD
      Blower speed HI
      A/C switch On
      Recirculation/fresh switch RECIRCULATION
      Interior temperature 25 to 35°C (77 to 95°F)

      Body Electrical > Air Conditioner > Trouble Codes

      Note

      If refrigerant pressure on the high pressure side becomes high, the DTC will be stored. It is necessary to operate the air conditioning system for a certain amount of time (approximately 10 minutes) because the DTC may be stored after the air conditioning operates for a while.

      Tech Tips

      When the outside air temperature is low (below -1.5°C (29.3°F)), the compressor stops due to operation of the thermistor assembly and the No. 1 cooler thermistor to prevent the evaporator from freezing. In this case, perform the inspection in a warm indoor environment.

      Result
      Result Proceed to
      DTC B1423/23 is output A
      DTC B1423/23 is not output B

      Note

      If the DTC was set due to an insufficient or excessive amount of refrigerant, the problem may have been solved after performing the previous step. However, the root cause of insufficient refrigerant may be refrigerant leaks. The root cause of excessive refrigerant may be adding too much refrigerant when the level was insufficient. Therefore, identify and repair the area where refrigerant leaks from as necessary.


    B
    A
  15. INSPECT AIR CONDITIONER PRESSURE SENSOR


    1. Install a manifold gauge set.

    2. Reconnect the B5 air conditioner pressure sensor connector.

    3. Turn the power switch on (IG).

    4. B003XPUC18
      *a

      Component with harness connected

      (Air Conditioning Amplifier Assembly)

      Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K11-9 (PRE) - K11-32 (SG-2)

      Refrigerant pressure: Normal pressure (less than 3025 kPa (30.8 kgf/cm2, 439 psi) and more than 176 kPa (1.8 kgf/cm2, 26 psi))

      0.74 to 4.71 V
      Result
      Proceed to
      OK
      NG

    OK
    NG
  16. REPAIR AIR CONDITIONING SYSTEM LEAK


    1. Identify the area where refrigerant leaks from.

      Click here

    2. Repair the identified area of the air conditioning system.

    3. Evacuate the air conditioning system.

      Result
      Proceed to
      NEXT

    NEXT
  17. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR)


    1. Disconnect the K11 air conditioning amplifier assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      B5-1 (-) - K11-32 (SG-2) Always Below 1 Ω
      K11-32 (SG-2) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG
  18. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER ASSEMBLY - AIR CONDITIONER PRESSURE SENSOR)


    1. Disconnect the K11 air conditioning amplifier assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      B5-3 (+) - K11-13 (S5-3) Always Below 1 Ω
      K11-13 (S5-3) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG